Apparatus for coating and/or impregnating a sheet material

ABSTRACT

A sheet being passed through a slit-shaped channel in a metering device is contacted on one or more sides with a coating and/or impregnating agent which is supplied through one or more feed openings in the walls of the channel. The size of the feed openings may be adjusted to vary the distribution of the coating and/or impregnating agent, and the contour of the slit-shaped channel may be adjusted e.g., to vary the pressure build-up within the channel.

United States Patent [151 3,698,355 Heijnis et a1. Oct. 17, 1972 I54]APPARATUS FOR COATING AND/OR 3,081,687 3/1963 Takats ..95/89IMPREGNATING A SHEET MATERIAL 896,504 8/1908 Adams ..1 18/412 [72]lnvenmrs: James W. I. Heijnis, Arnhem; 3,326,181 6/1967 Kllleen..118/411 Joseph T v. M. Geusgens Dieren 3,556,832 1/1971 Park ..118/410both of Netherlands 3,348,526 10/1967 Neubauer ..118/410 [73] Assignee:Aku N. V., Arnhem, Netherlands FOREIGN PATENTS OR APPLICATIONS Nov. 17 iGreat Britain i 1 PP ,140 Primary Examiner-Mervin Stein AssistantExaminer-Leo Millstein [30] Foreign Application Priority DataAttorney-Stevens, Davis, Mlller & Mosher Nov. 29, 1968 Netherlands..6817090 57 A T [52] U S Cl 118/411 I l8/410 1 133/313 A sheet beingpassed through a slit-shaped channel in [51] hit C1 80503/00 a meteringdevice is contacted on one or more Sides [58] Field of Search" 118/41041 l 412 216 with a coating and/or impregnating agent which is sup- 1plied through one or more feed openings in the walls of the channel. Thesize of the feed openings may be adjusted to vary the distribution ofthe coating and/or [56] References cued impregnating agent, and thecontour of the slit-shaped UNITED STATES PATENTS channel may be adjustede.g., to vary the pressure build-up within the channel. 346,869 8/1886Sherck & Batrg ..118/411 2,784,697 3/1957 Uhleen ..118/411 2 Claims, 3Drawing Figures APPARATUS FOR COATING AND/OR IMPREGNATING A SHEETMATERIAL The present invention relates to an apparatus for coatingand/or impregnating a sheet material. The sheet material is passedthrough a slit-shaped channel of a metering device in which a liquidcoating and/or impregnating agent is supplied through one or more feedopenings in the walls of the channel to one or both sides of the sheetmaterial.

This general coating device of forming laminated or impregnated articlesis known in the prior art, for example, Swiss Patent Specification No.381,851. In this prior art method, two or more layers of a sheetmaterial can be coated and/or impregnated on both sides and then thelayers are pressed against each other. In this process, each layer ofsheet material is passed through a slit shaped channel having a passageof constant height in which the coating and/or impregnating agent isapplied to the layer. The liquid treating agent is supplied to thelayers from openings in the channel walls with these openings beingconnected to a supply channel for the treating agent. This known methodhas the disadvantage that the distribution of the amount of treatingagent across the width of the sheet material cannot be varied tocompensate for fluctuations in the local take-up of the treating agentinto the sheet material. Depending on the manner in which the sheetmaterial is formed, the take-up of the treating agent may varyappreciably across the width of the sheet material, for example, in thecase where the sheet material exhibits differential density across itswidth. Moreover, in this known method, the total amount of coating orimpregnating agent to be applied can be controlled only by changing thesupply pressure at the beginning of the feed channel which communicateswith the feed openings. Also, the prior art device is not adaptable toobtain special effects by applying in predetermined manner to localizedareas of the sheet material an increased amount of coating or impregnating agent.

It is a principal object of the present invention to provide anapparatus for coating and/or impregnating sheet material which do nothave the aforementioned drawbacks of the prior art procedure. Inaccordance with the present invention, the amount of treating agent forcoating and/or impregnating the sheet material may be adjusted byvarying the size of the feed openings leading to the channel throughwhich the sheet material passes for the purpose of either varying thetotal amount of treating agent supplied and/or the distribution of thetreating agent across the width of the sheet material. By varying thesize of the various feed openings, it is possible to ensure that theamount of treating agent flowing through each opening can be set inconformity with the requirements to be satisfied by the product. Thus,during a production run it may be decided, depending upon the results ofvisual and other evaluations of the evenness and appearance of thecoated and/or impregnated sheet, to adjust the size of the feed openingsacross the sheet. In this manner, incorrect distribution of the treatingagent can be remedied quickly and easily. Such adjustment of the feedopenings will in general be necessary where the treating agentdistribution has changed as' a result of a different sheet materialbeing treated or as a result of the sheet material exhibiting differentthickness or density. In the latter situation, the total amount oftreating agent supplied should be adjusted to compensate for suchdifference.

In the practice of the invention, favorable results are obtained if thepressure drop across the feed openings is at least 0.1 kg/cm andpreferably from 1 to 2 kg/cm". By adjusting the feed opening(s) so thatthe magnitude of the outflow resistance is in the above range, it isfound that variations in the resistance to the passage through theimpregnating channel of the sheet material have hardly any appreciableinfluence on the amount of the treating agent. The reason for this isthat variations in resistance to the passage of the. sheet through theimpregnation channel are of a far lower magnitude than the outflowresistance of the treating agent so that these outflow resistancesdetermine the amount of treating agent which issues from the feedopenings.

The sheet material used in the practice of the invention preferably isformed of a sheet which substantially consists of threads or a fibermass. The sheets may be composed of continuous filaments or fibers ofthreadforming polymers such as polyamides such as nylon, polyesters suchas polyethylene terephthalate, polyvinyl compound such as polyvinylchloride, polyolefins such as polyethylene and polypropylene, cellulosederivatives, glass fibers, mineral fibers, etc.

In embodiments in which the treating material is supplied to both sidesof the sheet material, it is particularly effective if the treatingagent is supplied at exactly opposite points on both sides of the sheetmaterial; This method is of particular importance if coating orimpregnating agents with different properties are used on opposite sidesof the sheet material. This may be the case if the two sides of thefinal product are intended to have different functions. Moreover, thismethod permits the choice of having on the sides of the sheet materialdifferent adjustments of both the amounts and outflow resistances of thetreating agent. This is of particular importance where differenttreating agents are used, or when it is envisaged to influence the depthof penetration of the treating agent into the sheet material. Dependingon the intended end use of the product, the serviceability of theproduct is determined by mechanical properties, for instance, itsflexibility. These properties may be influenced by the depth ofpenetration of the treating agent.

According to a presently preferred very effective embodiment of theinvention, the coating or impregnating agent is fed through slotted feedopenings which extend across the entire width of the sheet material. Theshape of the slotted feed openings which may be adjusted is capable ofensuring a substantially uniform distribution of the treating agentacross the width of the sheet material. The feed opening slots extend inthe transverse direction of the metering channel preferably with theadjustable slots in the channel walls positioned exactly opposite eachother, and with. means for independently adjusting the opening of eachslot, for example, by adjustable bolts which may exert a push or pull onelastically deformable wall portions.

In accordance with another aspect of the invention, the metering deviceof the invention is provided with means for adjusting the sectional areaof the slit-shaped channel in which the sheet material is coated orimpregnated. By means of adjusting members, the walls of the channel maybe caused to take positions substantially parallel, converging ordiverging with respect to each other. This aspect of the invention is ofparticular importance because it enables an adjustment of the pressurebuild-up within the coating or impregnating channel. When the walls ofthe channel converge in the direction of travel of the sheet material,the sheet material is subjected to a rapid increase in pressure just asit enters the zone of the feed slots. Air entrapped in the sheetmaterial is driven out before the liquid treating agent which flowsthrough the adjustable slots reaches and penetrates the sheet materialin order to ensure uniform penetration across the width of the sheetmaterial. The air can escape in a direction pposite to the feeddirection of the sheet material. By changing the sectional area of theslit-shaped channel, it is possible to extend the zone of pressurebuild-up and also to influence the magnitude of'this pressure build-up.

In accordance with another embodiment of the invention in which thetreating agent is supplied to only one side of the slit-shaped channel.The members for adjusting the sectional area of the channel may beprovided on the opposite side of the channel and distributed across itswidth to cause elastic deformation of this wall of the channel so thatthe shape of the channel may as much as possible be adapted to the crosssectional shape of the sheet material. In this way, the desireddistribution pattern of the treating agent from its feed slot whichextends across the width of the channel is maintained as much aspossible while the treating agent is taken up by the sheet material.Consequently, the ratio of the amount of the treating agent to theamount of the sheet material may be maintained nearly constant acrossthe entire width of the sheet material.

The above and other objects, features and advantages of the inventionwill become more apparent from the following description of theaccompanying drawing wherein like reference numerals are utilized todesignate like parts throughout the several views.

FIG. 1 is an elevational view partly in section of one embodiment of thepresent invention.

FIG. 2 is a partial plan view of the embodiment of FIG. 1.

FIG. 3 is an elevational view partly in section of another embodiment ofthe invention in which the treating agent is supplied to only one sideof the sheet material and in which the shape of the sectional area ofthe slit-shaped channel is adjustable across its width.

Referring now to the drawing, and more particularly to FIG. 1, referencenumeral 1 designatesa slit-shaped channel through which the sheetmaterial to be treated is passed downwardly in the direction indicatedby the arrow. Within the channel an impregnating agent is supplied toboth sides of the sheet material via slots 2 and 3 in opposite sides ofthe channel. The slots 2 and 3 extend across the full width of the wallsof the slitshaped channel 1 with the slots being bounded by lower slitwalls 4 and 5 and upper slit walls 6 and 7. In this embodiment, thewalls 4 and 6 which bound slot 2 are separate parts which are clampedtogether by bolts 8. However, it is not necessary that these walls beseparate parts, and the same may be said for the walls 5 and 7 whichbound the slot 3. Although the direction of flow of the impregnatingagent from slots 2 and 3 is at right angles to the longitudinaldirection of the channel 1, this is not essential. For instance, thelongitudinal axes of the slots and the inlet portions of the meteringchannel may be at an acute angle to each other.

Each end of the slot 2 is bounded by a flat plate 9 which is pressedagainst the side faces of the wall parts 4 and 6 by means not shown toform a hermetic seal. Similarly, each end of the slot 3 is bounded byflat plates 10 which are pressed against the side faces of the wallparts 5 and 7 to form a hermetic seal.

An impregnating agent is fed to the slot 2 from a channel 1 1 which isbounded by the slit wall parts 4 and 6 and the two plates 9, with theimpregnating agent being fed to the channel through an inlet from asuitable source which is not shown. The wall parts 4 and 6 and the twoend plates 9 constitute an integral unit which is pivot-mounted insupports 20. The supports may be accurately displaced relative to astationary frame 13 for the purpose of adjusting the width 24 of thechannel 1.

Adjustment of the height of slot 2 is achieved by bolts 15 which have afine screw thread to enable close adjustment. A bolt 16 is fixedlyscrewed in the wall part 5 of the slit wall so that by turning the nut17 on bolt 16 the wall parts 4 and 6 which define the slot 2 are movedeither nearer together or farther apart. The elasticity of the wallparts 4 and 6 is chosen so that over the set height of the slot 2 thewall parts 4 and 6 will not be subject to plastic deformation.Adjustment of the height of slot 2 is carried out by first turning thebolt 15 to a setting constituting the chosen height which can be read bymeans of a pointer 18 and a scale 19, followed by turning the nut 17 toadjust the distance between the wall parts 4 and 6 until the bottom ofbolt 15 contacts the wall part 4.

Adjustment of the height of the slot 3 is effected in the same way. Thewall parts 5, 7 and the two end plates 10 similarly constitute anintegral unit which is pivot-mounted in supports 21 which are fixedlymounted on the frame 13.

By adjusting the height of slots 2 and 3 as described above, a desireddistribution of the impregnating agent across the width of channel 1 maybe obtained. The elastic deformation of the wall parts 4, 5, 6 and 7ensures that the height of the slots varies along a flowing line acrossthis length. With the aid of levers 22 and 23 operatively associatedwith supports 20 and 21, the position of the walls of channel 1 may bechanged so that these walls assume a parallel, a converging or divergingposition relative to each other.

It is preferred that the ends of the wall parts 4 and 5 adjacent thedischarge end of channel 1 be bevelled to an acute angle 39. The angle39 should preferably be from 45 to 60 and serves to prevent theimpregnating agent being left at the ends of the channel where it coulddecompose or repenetrate into the channel.

Heat exchange jackets 25 and 26 are provided to keep the wall parts 4 7at the desired temperature.

FIG. 3 illustrates another embodiment of the present invention in whichimpregnating agent is fed to only one side of the sheet material via aslot 2. The other side of the channel 1 is constituted by a wall 27which is elastically deformable across the width of the channel 1. Anumber of draw bolts 28 are distributed over the of the nuts 31 and thebolts 28, the wall 27 is drawn into contact with the ends of the setscrews 29. The elastic deformation of the wall 27 allows a flowingsectional I shape of the channel to be achieved. For temperatureregulation, a heat exchange medium may be passed through bores 35 in thewall 27.

Although preferred embodiments of the invention have been shown anddescribed with particularity, it will be appreciated that variousmodifications may be made therein without departing from the scope andspirit of the invention.

What is claimed is:

1. Apparatus for applying a fluid treating material to a sheet materialcomprising a plurality of wall parts defining a split-shaped channelthrough which the sheet material is passed, at least one of said wallparts being provided with at least one feed opening through which thefluid material for treating said sheet material is fed, said feedopening being in the form of a slot which extends in a directiontransverse to the travel of the sheet material and being formed betweenone of two wall portions which is elastically deformable and a pluralityof independent adjustable bolts engaging said deforma ble wall portionto permit deformation thereof for 10- cally adjusting the slot along itslength.

2. An apparatus for coating and/or impregnating a sheet material such aswebs of filaments or fibers, whichapparatus has a slit-shaped channelthrough which the sheet material may be passed,

one or two channel walls being provided with a slotted feed openingthrough which a treating agent may be supplied, characterized in thatalong the slit-shaped channel there are provided several independentlyadjustable means for locally varying the free outlet area of the passageof a feed slot, said adjustable means consisting of independently actingnuts which are screwed on bolts for causing a pull or push to be exertedon elastically deformable slot walls.

2. An apparatus for coating and/or impregnating a sheet material such aswebs of filaments or fibers, which apparatus has a slit-shaped channelthrough which the sheet material may be passed, one or two channel wallsbeing provided with a slotted feed opening through which a treatingagent may be supplied, characterized in that along the slit-shapedchannel there are provided several independently adjustable means forlocally varying the free outlet area of the passage of a feed slot, saidadjustable means consisting of independently acting nuts which arescrewed on bolts for causing a pull or push to be exerted on elasticallydeformable slot walls.